Re-iterating some of above as manufacturer I can advise that Weathering Steel TCBs are generally available in M24 diameter only, with the following lengths: 70, 80, 90, 100, 105, 110, 120, 125, 130, 140, 150, 160, 170, 180, 190, 200, 220, and 240 mm. CSK & alternative diameters can be manufactured bespoke - dependant on quantity.